KR20200006102A - Polyimide Varnishes and Methods for Making the Same - Google Patents

Abstract

An object of the present invention is to provide a polyimide film having high transparency and improved bending resistance to a plurality of bends, and a varnish capable of providing the same. The varnish includes the polymer (α) and the solvent (β). The polymer (α) is a polyimide or polyimide precursor. The varnish further includes at least one metal element belonging to a typical metal element having an atomic weight of 26 or more and 201 or less, or a transition metal element having an atomic weight of 26 or more and 201 or less, except for an alkali metal and an alkaline earth metal. At least 1 type of the said metallic element contained in the said varnish exists 0.05-500 ppm with respect to the said polymer ((alpha)).

Description

Polyimide Varnishes and Methods for Making the Same

The present invention relates to a polyimide varnish and a method for producing the same.

In recent years, foldable devices such as flexible display devices (also referred to as "flexible displays"), devices having curved surfaces such as organic EL light emitting devices (also referred to as "organic EL illumination") or organic EL displays have been studied. In a device having a collapsible device and a curved surface, it is considered to use a collapsible film instead of a hard substrate as a substrate for forming a surface protective layer, a color filter, a touch panel, a TFT, and the like.

Moreover, in the field of touch panel materials like a transparent electrode film, using a resin film as a board | substrate as a glass substitute is considered from a viewpoint of weight reduction, thinning, and flexible.

As a collapsible film, the use of a polyethylene terephthalate film (PET film), a polyethylene naphthalate film (PEN film), and a cycloolefin film (COP film) excellent in optical characteristics, for example, has been studied.

On the other hand, polyimide resins generally have excellent properties such as thermal oxidation resistance, heat resistance, heat radiation resistance, low temperature resistance, chemical resistance, and the like, and therefore, the use of a polyimide film as the collapsible film has also been considered.

Patent Document 1: International Publication No. 2016/158825 Patent Document 2: Japanese Patent Application Laid-Open No. 2004-161937 Patent Document 3: Japanese Patent Application Laid-Open No. 2004-107411 Patent Document 4: International Publication No. 2012/118020

[Non-Patent Document 1] Latest Polyimides (Foundation and Application), Japanese Polyimide Research Group, p. 113

Films used for optical devices, such as flexible display devices, which are required to bend repeatedly, are required to be not only foldable, but also excellent in optical properties and excellent in bending resistance to plural times of bending. Since the above-mentioned PET film, PEN film, and COP film have the fault that it is inferior to bending resistance, it is difficult to use it as a board | substrate of such a flexible optical device.

On the other hand, polyimide resins generally have excellent properties such as optical properties, bending resistance, thermal oxidation resistance, heat resistance, heat radiation resistance, low temperature resistance, and chemical resistance, and therefore, the inventors have found that polyimide resins such as those described in Patent Document 1 The adoption of a mid film as a board | substrate of a flexible optical device was examined. However, it turned out that the conventional polyimide film like that described in patent document 1 has room for the improvement of the bending tolerance with respect to multiple times of bending.

In order to solve the problem that the adhesiveness of the surface of a polyimide film is lacking, patent document 2 has more than 0 ppm 100 ppm of at least 1 sort (s) chosen from 6 types of metal elements of sodium, magnesium, potassium, iron, nickel, and copper. The polyimide film contained below is described. Similarly, patent document 3 makes chromium less than 10 ppm for the adhesive improvement of a polyimide film. However, since the polyimide film of patent document 2 and patent document 3 uses the monomer which has a rigid frame | skeleton, light transmittance is low and it is difficult to use it as a board | substrate of a colorless transparent flexible optical device.

Accordingly, one of the objects of the present invention is to provide a polyimide film having high transparency and having improved bending resistance to a plurality of bends and a varnish capable of providing the same.

MEANS TO SOLVE THE PROBLEM As a varnish containing a polyimide or a polyimide precursor, the inventors of this invention carried out earnest examination in order to solve the said subject, The specific amount of at least 1 sort (s) chosen from the metal element which belongs to a specific typical metal element or a transition metal element is specified. By using the varnish containing, it was found out that the said subject can be solved and came to complete this invention. That is, this invention is as follows.

[One]

A varnish containing a polymer (α) and a solvent (β),

The polymer (α) is a polyimide or polyimide precursor,

The varnish includes at least one metal element belonging to a typical metal element having an atomic weight of 26 or more and 201 or less, or a transition metal element having an atomic weight of 26 or more and 201 or less, except for an alkali metal and an alkaline earth metal.

The varnish in which at least 1 sort (s) of the said metal element contained in the said varnish exists 0.05-500 ppm with respect to the said polymer ((alpha)).

[2]

The varnish according to item 1, wherein the transmittance of light having a wavelength of 450 nm measured at an optical path length of 10 mm is 60% or more when the concentration of the polymer (α) in the solvent (β) is adjusted to 20 mass%.

[3]

The varnish according to item 1 or 2, wherein the metal element comprises at least one member selected from the group consisting of Zn, Zr, Cu, Cr, Mn, Co, Pd, Ni, Rh, Al, and Fe.

[4]

The varnish according to any one of items 1 to 3, wherein at least one of the metal elements included in the varnish is present in an amount of 0.05 to 100 ppm with respect to the polymer (α).

[5]

The varnish according to item 3, wherein the metal element comprises Zn.

[6]

The varnish according to item 3, wherein the metal element comprises Zr.

[7]

The varnish according to item 3, wherein the metal element comprises Cu.

[8]

The varnish according to item 3, wherein the metal element comprises Cr.

[9]

The varnish according to item 3, wherein the metal element includes at least one selected from the group consisting of Mn, Co, Pd, Ni, Rh, and Al.

[10]

The varnish according to item 3, wherein the metal element comprises Fe.

[11]

The metal element comprises Fe,

The varnish according to item 3, wherein Fe is present in 50 ppm to 500 ppm with respect to the polymer (α).

[12]

The varnish further includes a typical nonmetallic element selected from the group consisting of P and Si,

The varnish according to any one of items 1 to 9, wherein at least one of the typical nonmetallic elements included in the varnish is present in an amount of 0.05 to 100 ppm with respect to the polymer (α).

[13]

The varnish according to any one of items 1 to 12, wherein the polymer (α) is a polyimide.

[14]

The varnish according to item 13, wherein the solvent β is gamma -butyrolactone.

[15]

The varnish according to item 14, wherein the metal element comprises Cu.

[16]

The varnish according to item 1, wherein the total amount of the metal elements included in the varnish is 0.05 to 500 ppm with respect to the polymer (α).

[17]

The varnish according to any one of items 1 to 14, wherein the varnish is used for forming a polyimide layer of a flexible display device or a polyimide layer of an organic EL light emitting device.

[18]

The polyimide film obtained from the varnish of any one of items 1-17.

[19]

An organic EL light emitting device having the polyimide film described in item 18.

[20]

Flexible display device which has the polyimide film of item 18.

[21]

The flexible display device further includes a light source,

The polyimide film is the flexible display device according to item 20, wherein the light from the light source is disposed at a position such that light from the light source passes through the polyimide film and is output to the outside of the flexible device.

[22]

A flexible display device having a polyimide layer containing a polymer (α),

The polyimide layer contains at least one metal element belonging to a typical metal element having an atomic weight of 26 or more and 201 or less, or a transition metal element having an atomic weight of 26 or more and 201 or less, excluding an alkali metal and an alkaline earth metal.

At least 1 sort (s) of the said metal element contained in the said polyimide exists in 0.05-500 ppm with respect to the said polymer ((alpha)).

[23]

The flexible display device according to item 22, wherein at least one of the metal elements included in the polyimide layer is present in an amount of 0.05 to 100 ppm with respect to the polymer (α).

[24]

The flexible display device according to item 22, wherein the metal element comprises at least one selected from the group consisting of Zn, Zr, Cu, Cr, Mn, Co, Pd, Ni, Rh, Al, and Fe.

[25]

The flexible display device according to item 24, wherein the metal element contains at least one selected from the group consisting of Zn, Zr, Cu, and Cr.

[26]

The metal element comprises Fe,

The flexible display device according to item 24, wherein Fe is present at 50 to 500 ppm relative to the polymer (α).

[27]

The flexible display device according to item 22, wherein the total amount of the metal elements contained in the polyimide layer is 0.05 to 500 ppm with respect to the polymer (α).

[28]

The flexible display device further includes a light source,

The flexible display device according to item 27, wherein the polyimide layer is disposed at a position such that light from the light source passes through the polyimide layer and is output to the outside of the flexible display device.

[29]

As a method for producing a polyimide varnish, the method is

(a) dissolving diamine and an acid dianhydride in a solvent to produce a polyimide precursor,

(b) heating the polyimide precursor in the solvent to produce a polyimide,

In the step (b), at least one metal element selected from the group consisting of Zn, Zr, Cu, Cr, Mn, Co, Pd, Ni, Rh, Al and Fe is present in the solvent. Method of making varnishes.

[30]

The method of producing a polyimide varnish according to item 29, wherein the metal element comprises Cu.

According to the present invention, a polyimide film having high transparency and improved bending resistance to a plurality of bends and a varnish capable of providing the same are provided. Here, the above description should not be regarded as describing all the embodiments of the present invention and all the advantages relating to the present invention.

1: is a schematic diagram which shows the example of the bending test in this specification.
It is a schematic diagram for demonstrating the state of the film after a bending test.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention (henceforth "this embodiment") is described in detail. In addition, this invention is not limited to the following embodiment, It can variously deform and implement within the range of the summary. In this specification, the upper limit and lower limit of each numerical range can be combined arbitrarily.

Varnish

<Trace metal element>

The varnish of this embodiment contains a polymer (α) and a solvent (β). The varnish is at least one selected from a typical metal element having an atomic weight of 26 or more and 201 or less, or a metal element belonging to a transition metal element having an atomic weight of 26 or more and 201 or less, excluding an alkali metal and an alkaline earth metal (hereinafter, " It is also referred to as a "trace metal element."). At least one of the trace metal elements included in the varnish is present in an amount of 0.05 to 500 ppm relative to the polymer (α).

Although not limited to the theory, the varnish of the present embodiment contains a trace metal element, thereby improving the polymerization reactivity of the polyimide or polyimide precursor of the polymer (α), thereby increasing the molecular weight of the polymer (α) in the varnish, Or when the polyimide film is molded from the varnish, the molecular weight of the polymer (α) is increased, so that it is possible to provide a polyimide film having improved bend resistance to a plurality of bends.

Since alkali metals and alkaline earth metals have outermost electrons in the s orbit, it is presumed that there is little electronic interaction with organic molecules, and the influence of the polymer on the polymerization reaction is small. On the other hand, in the typical metal element or transition metal element, since outermost electrons or free electrons exist in p or d orbits whose spatial expansion is wider than s orbits, electronic interaction with organic molecules occurs, thereby polymerizing the polymer. It is assumed to have catalysis for the reaction.

Trace metal elements include zinc (Zn), zirconium (Zr), copper (Cu), chromium (Cr), manganese (Mn), cobalt (Co), palladium (Pd), and nickel (a typical metal element or a transition metal element). It is preferable to contain at least 1 sort (s) chosen from the group which consists of Ni), rhodium (Rh), aluminum (Al), and iron (Fe). Trace metal elements preferably comprise zinc, more preferably zinc and copper, still more preferably zinc, copper and iron, still more preferably zinc, copper, iron and zirconium And most preferably zinc, copper, iron, zirconium and chromium.

Although the mechanism of action of the preferable trace metal element mentioned above with respect to the polymerization reaction of a polyimide or a polyimide precursor is unclear, it is estimated that it promotes a polymerization reaction by electronic interaction with organic molecules.

At least one of the trace metal elements contained in the varnish is preferably 0.05 ppm or more, more preferably 0.1 ppm or more, still more preferably 0.5 ppm or more, still more preferably 1.0 ppm or more with respect to the polymer (α). More preferably, it is 4.0 ppm or more.

At least one of the trace metal elements included in the varnish is preferably 500 ppm or less, more preferably 400 ppm or less, more preferably 300 ppm or less, and more preferably 200 ppm or less with respect to the polymer (α). More preferably, it is 100 ppm or less, 90 ppm or less may be sufficient, 80 ppm or less may be sufficient, 70 ppm or less may be sufficient, and 60 ppm or less may be sufficient.

As for the total amount of the trace metal element contained in a varnish, 0.05-500 ppm is preferable with respect to a polymer ((alpha)) from a transparency point of a film.

When there is much content of a trace metal element, polyimide will become easy to color. Although the mechanism of the action of the trace metal element is unclear, it is presumed that the polyimide forms an association or a complex by interaction with the metal element, so that absorption of visible light occurs and the color becomes easy to be colored. It is estimated that coloring by metal oxide also causes coloring when it is set as a polyimide film.

When the trace metal element contains copper, the lower limit of the amount of copper relative to the polymer (α) is preferably 0.05 ppm or more, more preferably 0.1 ppm or more, even more preferably 1 ppm or more, and the upper limit is preferably Is 100 ppm or less, more preferably 90 ppm or less, even more preferably 50 ppm or less.

When the trace metal element contains at least one selected from the group consisting of manganese, cobalt, palladium, nickel, rhodium and aluminum, at least one of the metal elements included is preferably 0.05 to the polymer (α). It is ppm or more, More preferably, it is 0.07 ppm or more, More preferably, it is 0.1 ppm or more, Preferably it is 500 ppm or less, More preferably, it is 100 ppm or less.

When the trace metal element contains iron, the lower limit of the amount of iron relative to the polymer (α) is preferably 0.05 ppm or more, more preferably 50 ppm or more, and the upper limit is preferably 500 ppm or less, more preferably Is 100 ppm or less.

When iron content exists in the range of 50 ppm-100 ppm, since bending resistance and transparency of a film can be compatible, it is preferable. Since iron has a property of easily interacting with oxygen, the electronic interaction between iron and organic molecules is reduced by the interaction of dissolved oxygen with iron in a solvent, and the performance of promoting the polymerization reaction is higher than that of Zn or Cu. It is estimated to fall. Therefore, in order to fully promote a polymerization reaction, without performing degassing of a complicated solvent, etc., addition of 50 ppm or more is suitable.

When the trace metal element contains zirconium, the lower limit of the amount of zirconium relative to the polymer (α) is preferably 0.05 ppm or more, more preferably 0.07 ppm or more, even more preferably 0.1 ppm or more, and the upper limit is preferably Is 100 ppm or less, more preferably 90 ppm or less, even more preferably 50 ppm or less.

When the trace metal element contains zinc, the lower limit of the amount of zinc relative to the polymer (α) is preferably 0.05 ppm or more, more preferably 0.1 ppm or more, even more preferably 0.2 ppm or more, and the upper limit is preferably Is 150 ppm or less, more preferably 120 ppm or less, even more preferably 100 ppm or less.

When the trace metal element contains chromium, the lower limit of the amount of chromium relative to the polymer (α) is preferably 0.05 ppm or more, more preferably 1.0 ppm or more, still more preferably 2.0 ppm or more, and the upper limit is preferably Is 150 ppm or less, more preferably 120 ppm or less, even more preferably 100 ppm or less.

<Trace nonmetallic element>

In addition to the said trace metal element, the varnish of this embodiment further contains 0.05-100 ppm of nonmetallic elements (also called a "trace nonmetallic element" in this specification) with respect to the polymer ((alpha)). It is preferable that trace nonmetallic elements are phosphorus (P) and / or silicon (Si), for example. When the varnish of this embodiment contains a trace nonmetallic element, since the intensity | strength of a polyimide film improves, it is preferable. The lower limit of the content of the trace non-metallic element with respect to the polymer (α) is more preferably 0.1 ppm or more, still more preferably 1.0 ppm or more, and the upper limit is more preferably 100 ppm or less, even more preferably 50 ppm or less.

Although the mechanism of action of phosphorus and / or silicon is unclear, it is presumed that phosphorus and / or silicon may interact with the above-described trace metal elements, thereby increasing the polymerization promoting ability of the trace metal elements.

〈Light Transmittance〉

The varnish of this embodiment has a transmittance of 45% or more of light having a wavelength of 450 nm measured at an optical path length of 10 mm when the solid content concentration in the solvent is adjusted to 20% by mass, preferably 50% or more, and more preferably 55 % Or more, More preferably, it is 60% or more, More preferably, it is 70% or more, More preferably, it is 80% or more. The upper limit of the transmittance of wavelength 450 nm light is not particularly limited, but may be less than 100%, 99% or less, 98% or less, 95% or less, or 90% or less.

The polyimide varnish of the present embodiment has a transmittance of light of wavelength 400 nm measured at an optical path length of 10 mm when the solid content concentration in the solvent is adjusted to 20% by mass, preferably 10% or more, more preferably 10%. Preferably it is 20% or more, More preferably, it is 30% or more, More preferably, it is 40% or more, More preferably, it is 50% or more. The upper limit of the transmittance of the wavelength of 400 nm light is not particularly limited, but may be less than 100%, 90% or less, 80% or less, or 70% or less.

The varnish of this embodiment can be suitably used as a film substrate of a flexible optical device by having the said structure in addition to having the improved bending tolerance with respect to several times of bending. The method for adjusting the light transmittance in the above range is not limited, but the kind and content of the solvent contained in the varnish, the diamine and acid dianhydride monomer units constituting the polyimide or polyimide precursor, the polyimide or the polyimide precursor It can adjust by changing the molecular weight, the kind of arbitrary additives, content rate, etc. For example, by using the polyimide represented by Formula (1) described below, it becomes easier to adjust the light transmittance to the above range.

<menstruum>

The solvent β is not particularly limited. As the solvent, a polar solvent is useful, and examples of the polar solvent include a phenol solvent, an amide solvent, a lactone solvent, a sulfoxide solvent, a ketone solvent, and an ester solvent. Examples of the phenol solvents include m-cresol. Examples of the amide solvents include N-methyl-2-pyrrolidone (NMP), N, N-dimethylformamide (DMF) and N, N-dimethylacetamide (DMAc). Examples of the lactone solvents include γ-butyrolactone (GBL), δ-valerolactone, ε-caprolactone, γ-crotonlactone, γ-hexanolactone, α-methyl-γ-butyrolactone, and γ-valero Lactone, (alpha)-acetyl- (gamma) -butyrolactone, and (delta) -hexanolactone are mentioned. Examples of the sulfoxide solvent include N, N-dimethyl sulfoxide (DMSO). Examples of the ketone solvents include acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. Examples of the ester solvent include methyl acetate, ethyl acetate, butyl acetate and dimethyl carbonate. Among these, NMP and GBL are preferable from the viewpoint of solubility. From the viewpoint of further reducing the yellowness (YI) of the film, GBL is more preferable.

<Polymer (α)>

In this embodiment, the polymer (α) contained in the varnish is a polyimide or a polyimide precursor. The lower limit of the molar ratio of the diamine to the acid dianhydride contained in the polyimide or polyimide precursor as the polymerization unit is preferably 0.95 or more, more preferably 0.96 or more, even more preferably 0.965 or more, even more preferably 0.97 or more. The upper limit is less than 1.00, more preferably less than 0.995, still more preferably less than 0.993, even more preferably less than 0.99. When the molar ratio of the diamine to the acid dianhydride contained in the polyimide or polyimide precursor as the polymerized unit is 0.95 or more and less than 1.00, the coating defect of the varnish can be suppressed and high transparency can be obtained.

The varnish of this embodiment may be either a polyimide varnish (that is, at least part of the polymer (α) is a polyimide) or a polyimide precursor varnish (that is, the polymer (α) is a polyimide precursor). . The polyimide varnish is preferable from the viewpoint of the strength of the intermediate film (the film without the surface stickiness after the conditioning) when the varnish is processed into a roll film. In the case of a polyimide varnish, the intermediate film at the time of processing into a roll film is strong in breaking, and it is easy to apply to a roll film processing process.

It is preferable that the varnish which concerns on this embodiment contains the polyimide represented by following formula (1) as a polymer ((alpha)), or the precursor of this polyimide.

In said formula (1), A is a divalent organic group, B is a tetravalent organic group, n is two or more.

A in formula (1)

The polyimide contained in a polyimide varnish can produce | generate an acid dianhydride and diamine as a raw material. A of Formula (1) can be obtained from diamine.

Moreover, in this embodiment, as A in Formula (1), the structure represented by following formula (A-1), following formula (A-2), following formula (A-3), and following formula (A-) It is preferable to include at least 1 sort (s) of the structure represented by 4).

In said formula (A-2), X is a divalent organic group chosen from following formula (X-1)-formula (X-3).

A is 0 or 1 in said Formula (A-3).

The structure represented by formula (A-1) is derived from 3,3'-diaminodiphenyl sulfone (hereinafter also referred to as 3,3'-DDS), and is represented by formula (A-2) And the structure represented by combining Formula (X-1) (corresponding to Formula (A-5)) is 4,4'-Diaminodiphenyl Sulfone (hereinafter referred to as 4,4'-). And a structure represented by combining formula (A-2) and formula (X-2) is α, α'-bis (4-aminophenyl) -1,4-diisopropylbenzene (hereinafter referred to as DDS). , Also referred to as BAPDB), and the structure represented by combining formula (A-2) and formula (X-3) is derived from 4,4'-bis (4-aminophenoxybiphenyl) (hereinafter also referred to as BAPB). When a is 0, the structure represented by formula (A-3) is derived from cyclohexyldiamine (hereinafter also referred to as CHDA), and when a is 1, 1,4-bis (aminomethyl) cyclohexane (Hereinafter also referred to as 14BAC) derived, and the structure represented by formula (A-4) is derived from bis (aminomethyl) norbornane (hereinafter referred to as BA Also known as NBDA). However, it is not limited to these compounds.

Formula (A-5) of the combination of Formula (A-2) and Formula (X-1) is shown below.

Formula (A-6) of the combination of Formula (A-2) and Formula (X-2) is shown below.

Formula (A-7) of the combination of Formula (A-2) and Formula (X-3) is shown below.

The polyimide varnish in this embodiment contains the structure (3,3'- diamino diphenyl sulfone derived) represented by Formula (A-1) as A of Formula (1) as an essential repeating unit, Moreover, the polyimide containing any 1 or more types of structures represented by Formula (A-2), Formula (A-3), and Formula (A-4) as a repeating unit combined with the structure of Formula (A-1) is used. It is preferable to contain.

The polyimide contained in the polyimide varnish in the present embodiment has a low yellowness (hereinafter referred to as "YI") by including the repeating unit described above, and has a low retardation (hereinafter referred to as "Rth" ( It is also possible to provide a polyimide film having a small) and excellent in bending resistance. In addition, it is preferable that YI is as low as possible. When YI is low, the coloring of a polyimide film can be reduced and visibility of a touch panel, an organic EL light emitting device, a flexible display device, etc. can be improved. Therefore, it is preferable to make YI as low as possible and to raise the total light transmittance in visible light. The coloring of the polyimide is believed to originate from the formation of a charge transfer complex (hereinafter referred to as a "CT complex") within and between the polyimide molecules. It is considered that the structures represented by formulas (A-1) to (A-4) all inhibit the formation of the CT complex between polyimide molecules by bending of the main chain. Above all, the structures represented by the formulas (A-1) and (A-5) can weaken the electron donating of the N atom of the imide group due to the electron withdrawing property of the SO ₂ group, making it difficult to form a CT complex. It is especially preferable because it is considered.

Absorption of the visible light of the aromatic polyimide also causes coloring of the polyimide. Since the alicyclic structures of the formulas (A-3) and (A-4) have less π electrons in the conjugated system, it is considered that absorption of visible light can be reduced as compared with the aromatic polyimide.

It is thought that the solubility of a polyimide improves the one with low polyimide orientation. It is thought that the structures represented by formulas (A-1) to (A-4) all exhibit excellent solubility because the orientation of the polyimide molecules decreases due to bending of the main chain. Among them, the structure represented by the formula (A-1) has a curved structure of SO ₂ group and a curved structure coexisting by the bonding of the 3 position and the 3 'position, so that the orientation of the polyimide molecule remarkably decreases, It is thought to express excellent solubility.

Thus, the polyimide contained in the polyimide film in this embodiment is a structure represented by Formula (A-1) as A of Formula (1), Formula (A-2), and Formula (A-). It is preferable to include any 1 or more types of structures represented by 3) and Formula (A-4).

By copolymerizing the structure represented by formula (A-1) and the structure represented by formula (A-5), the molecular weight of a polyimide increases, and the bending resistance of the film produced using this polyimide can be improved more. . At least one or more structures selected from the structures represented by formulas (A-2), (A-3), and (A-4) while having at least a structure represented by formula (A-1) The same effect is exhibited also about the polyimide which has.

In this embodiment, it is suitable to use at least the structure represented by Formula (A-1) and the structure represented by Formula (A-5). Hereinafter, the structure which used both 3,3'-DDS and 4,4'-DDS as a diamine is demonstrated.

The structural unit represented by Formula (A-1) can be obtained from a 3,3'-DDS component as mentioned above. The structure represented by formula (A-1) is a site | part for expressing solubility in a solvent.

The structural unit represented by Formula (A-5) can be obtained from 4,4'-DDS. The structure represented by Formula (A-5) expresses a glass transition temperature (Tg) in 250-350 degreeC in the polyimide film which heated and dried the varnish obtained by melt | dissolving the polyimide of this embodiment in a solvent. You can.

In this embodiment, it is preferable to contain both the structure represented by Formula (A-1) and the structure represented by Formula (A-5). It is preferable to introduce the structural unit represented by Formula (A-1) from the viewpoint of the solubility of a polyimide. The structural unit represented by formula (A-5) is preferable from a viewpoint of high glass transition temperature (Tg). By containing both the structure represented by the formula (A-1) and the structure represented by the formula (A-5), the solubility of the polyimide, the elongation at break of the film, and the high glass transition temperature (Tg), which cannot be achieved alone, respectively. ) Can be obtained without compromising colorless transparency or high total light transmittance.

In order to reduce Rth of a film, it is necessary to reduce the refractive index difference of the in-plane direction and out-of-plane direction of a film. Although not limited to the theory, the structure represented by the general formula (A-1) and the general formula (A-5) have a structure in which the SO ₂ group is bent and an sp ² orbit, and thus the bending structure is fixed. Therefore, as mentioned above, when the orientation of a polyimide molecule falls, when a varnish is coated and a film is produced, the structure represented by general formula (A-1) and the aromatic group contained in general formula (A-5) are one direction. It seems to exist at random without being lined up. That is, when the structure represented by general formula (A-1) and general formula (A-5) exist in a polyimide skeleton, it is thought that the refractive index difference of in-plane direction and out-of-plane direction reduces, and Rth of a film is reduced.

In this embodiment, the composition ratio ((A-1) / (A-2)-(A-4)) of the structure of Formula (A-1) and the structure of Formula (A-2)-Formula (A-4) It is preferable that it is 2/8-8/2 by molar ratio from a viewpoint that the bending resistance of a polyimide film can further be improved. In particular, in the case of having the structure represented by formula (A-5) as formula (A-2), the composition ratio of the structure of formula (A-1) and the structure of formula (A-5) ((A-1) / ( It is preferable that A-5)) exists in the range of 2/8-6/4 by molar ratio, and it is more preferable that it is the range of 3/7-4/6. That is, when Formula (A-1) makes 100 mol% whole quantity of A in Formula (1), it is preferable that they are 20 mol% or more and 60% or less. When formula (A-5) makes 100 mol% whole quantity of A in Formula (1), it is preferable that they are 40 mol% or more and 80% mol% or less.

In addition, a polyimide removes at least 1 sort (* 1: single formula (A-5)) of the structure of Formula (A-1), and the structure of Formula (A-2) ^{* 1} -Formula (A-4). ), These composition ratios ((A-1) / (A-2) ^{* 1} to (A-4)) (* 1: except for the single type (A-5)) are 5/5 in a molar ratio. -8/2 is preferable.

As mentioned above, only the 4,4'-DDS component derived (structure represented by Formula (A-5)) originates in a diamine component, and the molecular weight of a polyimide falls and the bending resistance of a film | membrane falls. For this reason, in this embodiment, it is an isomer derived from a 4,4'-DDS component, and originates in the 3,3'-DDS component which becomes a structure where the monomer skeleton was curved when seen from the 4,4'-DDS component origin (formula (A -1), and at this time, it is preferable to improve the bending resistance while increasing the molecular weight by making the 3,3'-DDS component derived less than the 4,4'-DDS component derived. Can be.

Moreover, in the range which can express the breaking elongation made into the objective, More preferably, in the range which can express the target glass transition temperature (Tg), Formula (A-1) and Formula (A-5) It may contain a small amount of structural units other than the structural unit represented by. That is, the polyimide which concerns on this embodiment may also contain structural units derived from diamine components other than 4,4'-DDS and 3,3'-DDS in the range which does not impair the performance. For example, aromatic diamine having 6 to 30 carbon atoms is mentioned as a preferred embodiment.

Specifically, 2,2'-bis (trifluoromethyl) benzidine (TFMB), 1, 4- diamino benzene, 4-aminobenzenesulfonic acid 4-aminophenyl ester, 4-aminobenzenesulfonic acid-3-amino Phenyl ester, 3-aminobenzenesulfonic acid-3-aminophenyl ester, 2-aminobenzenesulfonic acid-2-aminophenyl ester, 2,2'-dimethyl4,4'-diaminobiphenyl, 1,3-diaminobenzene , 4-aminophenyl4'-aminobenzoate, 4,4'-diaminobenzoate, 4,4 '-(or 3,4'-, 3,3'-, 2,4'-) diaminodi Phenylether, 4,4 '-(or 3,3'-) diaminodiphenylsulfide, 4,4'-benzophenonediamine, 3,3'-benzophenonediamine, 4,4'-di (4- Aminophenoxy) phenylsulfone, 4,4'-di (3-aminophenoxy) phenylsulfone, 4,4'-bis (4-aminophenoxy) biphenyl, 1,4-bis (4-aminophenoxy ) Benzene, 1,3-bis (4-aminophenoxy) benzene, 2,2'-bis {4- (4-aminophenoxy) phenyl} propane, 3,3 ', 5,5'-tetramethyl- 4,4'-diaminodi Phenylmethane, 2,2'-bis (4-aminophenyl) propane, 2,2 ', 6,6'-tetramethyl-4,4'-diaminobiphenyl, 2,2', 6,6'- Tetratrifluoromethyl-4,4'-diaminobiphenyl, bis {(4-aminophenyl) -2-propyl} 1,4-benzene, 9,9-bis (4-aminophenyl) fluorene, 9 , 9-bis (4-aminophenoxyphenyl) fluorene, 3,3'-dimethylbenzidine, 3,3'-dimethoxybenzidine and 3,5-diaminobenzoic acid, 2,6-diaminopyridine, 2, 4-diaminopyridine, bis (4-aminophenyl-2-propyl) -1,4-benzene, 3,3'-bis (trifluoromethyl) -4,4'-diaminobiphenyl (3,3 '-TFDB), 2,2'-bis [3 (3-aminophenoxy) phenyl] hexafluoropropane (3-BDAF), 2,2'-bis [4 (4-aminophenoxy) phenyl] hexa Fluoropropane (4-BDAF), 2,2'-bis (3-aminophenyl) hexafluoropropane (3,3'-6F), 2,2'-bis (4-aminophenyl) hexafluoropropane The structural unit derived from aromatic diamine components, such as (4,4'-6F), is mentioned.

9,9-bis (4-aminophenyl) fluorene and 9,9-bis (4-aminophenoxyphenyl) fluorene can be introduced when adjusting Rth because the fluorene skeleton has negative intrinsic birefringence. have.

Also 2,2'-bis (trifluoromethyl) benzidine (TFMB), 3,3'-bis (trifluoromethyl) -4,4'-diaminobiphenyl (3,3'-TFDB), 2 , 2'-bis [3 (3-aminophenoxy) phenyl] hexafluoropropane (3-BDAF), 2,2'-bis [4 (4-aminophenoxy) phenyl] hexafluoropropane (4- BDAF), 2,2'-bis (3-aminophenyl) hexafluoropropane (3,3'-6F), 2,2'-bis (4-aminophenyl) hexafluoropropane (4,4'- 6F) can suppress formation of the CT complex between molecules of the polyimide by introduction of bulk steric hindrance of a fluorine atom, and can be introduced to lower the YI of the film.

In addition, the structural unit derived from 2,2'-bis (trifluoromethyl) benzidine (TFMB) is represented by the following formula (A-8).

B in Formula (1)

Next, B of Formula (1) is demonstrated. In the formula (1), B, the structural unit can be obtained from an acid 2 anhydride.

In the present embodiment, the structural unit derived from the acid dianhydride component contained in the polyimide may be the same molecule or may be a molecule having a different structure.

It is preferable that the structural unit represented by B is a structural unit represented by Formula (B-1)-a formula (B-4).

In this embodiment, it is preferable to include at least 1 or more of the structure represented by following formula (B-1)-following formula (B-4) as B in Formula (1).

In said formula (B-1), Y is either of the structures chosen from a following formula (Y-1)-a following formula (Y-3).

The structure represented by combining formula (B-1) and formula (Y-1) (corresponding to the structure of formula (B-5)) is derived from 4,4'-oxydiphthalic acid dianhydride (hereinafter also referred to as ODPA). The structure represented by combining formula (B-1) and formula (Y-2) is derived from 4,4 '-(hexafluoroisopropylidene) diphthalic acid dianhydride (hereinafter also referred to as 6FDA) The structure represented by combining (B-1) and formula (Y-3) is derived from 9,9-diphenylfluorene dianhydride (hereinafter also referred to as DPFLDA), and is represented by formula (B-2). Is derived from hydroxypyromellitic dianhydride (hereinafter also referred to as HPMDA), and the structure represented by formula (B-3) is bicyclo [2,2,2] oct-7-ene-2,3,5, A structure derived from 6-tetracarboxylic dianhydride (hereinafter also referred to as BODA or BCDA) and represented by formula (B-4) is 1,3,3a, 4,5,9b-hexahydro-5- (tetra Derived from hydro-2,5-dioxo-3-furanyl) naphtho [1,2-c] furan-1,3-dione (hereinafter also referred to as TDA).

Since DPFLDA has a negative intrinsic birefringence, the fluorene skeleton can be introduced when adjusting Rth.

The polyimide which concerns on this embodiment contains the structural unit derived from the acid 2 anhydride component other than the structural unit represented by said Formula (B-1)-said Formula (B-4) in the range which does not impair the performance. Also good.

For example, the compound is preferably selected from an aromatic tetracarboxylic dianhydride having 8 to 36 carbon atoms, an aliphatic tetracarboxylic dianhydride having 6 to 50 carbon atoms, and an alicyclic tetracarboxylic dianhydride having 6 to 36 carbon atoms. . Carbon number here also contains the number of carbon contained in a carboxyl group.

More specifically, as an aromatic tetracarboxylic dianhydride having 8 to 36 carbon atoms, 4, pyromellitic dianhydride (hereinafter also referred to as PMDA), 1,2,3,4-benzenetetracarboxylic acid 2 Anhydride, 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride, 2,2', 3,3'-benzophenonetetracarboxylic dianhydride, 3,3 ', 4,4'- Biphenyltetracarboxylic dianhydride (hereinafter also referred to as BPDA), 3,3 ', 4,4'-diphenylsulfontetracarboxylic dianhydride, 2,2', 3,3'-biphenyltetra Carboxylic acid dianhydride, methylene-4,4'-diphthalic acid dianhydride, 1,1'-ethylidene-4,4'-diphthalic acid dianhydride, 2,2'-propylidene-4,4'-di Phthalic acid dianhydride, 1,2-ethylene-4,4'-diphthalic acid dianhydride, 1,3-trimethylene-4,4'-diphthalic acid dianhydride, 1,4-tetramethylene-4,4'-di Phthalic acid dianhydride, 1,5-pentamethylene-4,4'-diphthalic acid dianhydride, thio-4,4'-diphthalic acid dianhydride, sulfonyl-4,4'-diphthalic acid dianhydride, 1,3- Vis ( 3,4-dicarboxyphenyl) benzene dianhydride, 1,3-bis (3,4-dicarboxyphenoxy) benzene dianhydride, 1,4-bis (3,4-dicarboxyphenoxy) benzene dianhydride, 1,3-bis [2- (3,4-dicarboxyphenyl) -2-propyl] benzene 2 anhydride, 1,4-bis [2- (3,4-dicarboxyphenyl) -2-propyl] benzene 2 Anhydride, bis [3- (3,4-dicarboxyphenoxy) phenyl] methane dianhydride, bis [4- (3,4-dicarboxyphenoxy) phenyl] methane dianhydride, 2,2'-bis [3 -(3,4-dicarboxyphenoxy) phenyl] propane 2 anhydride, 2,2'-bis [4- (3,4-dicarboxyphenoxy) phenyl] propane 2 anhydride (hereinafter also referred to as BPADA), Bis (3,4-dicarboxyphenoxy) dimethylsilane dianhydride, 1,3-bis (3,4-dicarboxyphenyl) -1,1 ', 3,3'-tetramethyldisiloxane dianhydride, 2, 3,6,7-naphthalene tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic dianhydride, 1,2,5,6-naphthalene tetracarboxylic dianhydride, 3,4, 9,10-perylenetetracarboxylic dianhydride, 2,3,6,7- Tra, and the like metallocene tetracarboxylic dianhydride, phenanthrene-1,2,7,8- tetracarboxylic acid dianhydride.

Examples of the aliphatic tetracarboxylic dianhydride having 6 to 50 carbon atoms include ethylene tetracarboxylic dianhydride, 1,2,3,4-butane tetracarboxylic dianhydride, and the like.

Examples of the alicyclic tetracarboxylic dianhydride having 6 to 36 carbon atoms include 1,2,3,4-cyclobutanetetracarboxylic dianhydride (hereinafter also referred to as CBDA), cyclopentanetetracarboxylic dianhydride, Cyclohexane-1,2,3,4-tetracarboxylic dianhydride, 3,3 ', 4,4'-bicyclohexyltetracarboxylic dianhydride, carbonyl-4,4'-bis (cyclohexane -1,2-dicarboxylic acid) 2 anhydride, methylene-4,4'-bis (cyclohexane-1,2-dicarboxylic acid) 2 anhydride, 1,2-ethylene-4,4'-bis ( Cyclohexane-1,2-dicarboxylic acid) 2 anhydride, 1,1'-ethylidene-4,4'-bis (cyclohexane-1,2-dicarboxylic acid) 2 anhydride, 2,2'- Propylidene-4,4'-bis (cyclohexane-1,2-dicarboxylic acid) 2 anhydride, oxy-4,4'-bis (cyclohexane-1,2-dicarboxylic acid) 2 anhydride, thio -4,4'-bis (cyclohexane-1,2-dicarboxylic acid) 2 anhydride, sulfonyl-4,4'-bis (cyclohexane-1,2-dicarboxylic acid) 2 anhydride, rel- [1S, 5R, 6R] -3-oxabi Chloro [3,2,1] octane-2,4-dione-6-spiro-3 '-(tetrahydrofuran-2', 5'-dione), 4- (2,5-dioxotetrahydrofuran- 3-yl) -1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic acid dianhydride, ethylene glycol-bis- (3,4-dicarboxylic acid dianhydride phenyl) ether, 4, 4'-biphenyl bis (trimelitic acid monoester acid dianhydride) etc. are mentioned.

In said Formula (B-1), Formula (Y-1) and Formula (Y-2) are a viewpoint of the solubility to the solvent of a polyimide, and YI and retardation (Rth) reduction when it is set as a polyimide film. Preferred at In addition, since formula (Y-3) has negative intrinsic birefringence, it is preferable from a viewpoint of the reduction of YI and retardation (Rth), and the glass transition temperature (Tg) when it is set as a polyimide film.

The said Formula (B-2)-a formula (B-4) are preferable from a viewpoint of the solubility to the solvent of a polyimide, and YI reduction when it is set as a polyimide film.

From the viewpoints of the solubility of the polyimide in the solvent, the high total light transmittance, the low YI, the high elastic modulus, and the high elongation at break when the polyimide film is used, as B in the formula (1), the following formula (B-) is a component derived from ODPA. It is particularly preferable to include the structure represented by 5). Of the polyimide represented by the formula (1), in the structural unit B derived from the acid 2 anhydride, the formula (B-5) is preferably 50 mol% or more, more preferably 80 mol% or more with respect to the entire acid 2 anhydride. 100 mol% may be sufficient.

It is preferable that the polyimide which concerns on this embodiment mainly includes the unit 1 represented by following formula (2), and the unit 2 represented by following formula (3).

In the present embodiment, in the case of further including units other than the unit 1 and the unit 2, the content of units other than the unit 1 and the unit 2 is determined by the unit 1 and the unit 2. Less than content is preferable. These units may be bonded alternately in the polymer chain, may be bonded in a permutation, or these units may be bonded at random.

From the viewpoint of obtaining high breaking elongation and low Rth in the polyimide film, the weight average molecular weight (Mw) of the polyimide is preferably 10,000 or more, more preferably 25,000 or more, and particularly preferably 30,000 or more. Moreover, it is preferable that the weight average molecular weight (Mw) of a polyimide is 1,000,000 or less, It is more preferable that it is 500,000 or less, It is especially preferable that it is 250,000 or less. When the weight average molecular weight is 1,000,000 or less, solubility in a solvent is also good, and coating can be performed without spreading to a desired film thickness during processing such as coating, and a low Rth film can be obtained. It is preferable that a weight average molecular weight is 30,000 or more from a viewpoint of obtaining high breaking elongation and low Rth especially in a polyimide film. Here, a weight average molecular weight means the molecular weight measured by gel permeation chromatography (henceforth "GPC") using polystyrene of a known number average molecular weight as a standard.

The polyimide represented by the said Formula (1) proved also that the experiment mentioned later that the solubility to a solvent was excellent. Therefore, by using the polyimide represented by Formula (1), the varnish with desired characteristics can be obtained by a simple process. According to the polyimide varnish of this embodiment, since polyimide is melt | dissolving suitably, when a varnish is apply | coated on a coating surface, a gel-like thing does not generate | occur | produce and the film excellent in smoothness can be formed. For this reason, a resin layer of uniform thickness can be formed and high bending resistance can be obtained.

<< manufacturing method of polyimide varnish >>

The manufacturing method of the polyimide varnish of this embodiment includes (a) dissolving a diamine and an acid dianhydride in a solvent to produce a polyimide precursor, and (b) heating the said polyimide precursor to produce a polyimide. do. In one embodiment, the polyimide varnish is prepared by, for example, dissolving an acid dianhydride component and a diamine component in a solvent such as an organic solvent to produce a polyimide precursor, and (b) an azeotropic solvent such as toluene, and the like. The polyimide precursor can be prepared as a polyimide solution containing a polyimide and a solvent by heating the polyimide precursor and generating a polyimide while removing water generated in the imidization out of the system.

The method and timing of adding the trace metal element and any nonmetal trace element are not limited. Regarding the addition method, the trace metal element and trace non-metal element may be added together with a raw material used for producing the polyimide varnish, such as a solvent, diamine and / or acid dianhydride. Additionally or alternatively, the trace metal element and trace non-metal element may be added separately from the raw material used for producing the polyimide varnish. Regarding the addition timing, the trace metal element and the trace nonmetal element are before the step (a), between the step (a), after the step (a) and before the step (b), between the step (b) and / or the step (b). ) Can be added after. Preferably, in step (b), trace metal elements and trace nonmetal elements are present in the solvent. More preferably, the trace metal element and trace nonmetallic element are present in the solvent during step (b) by adding in the solvent together with the diamine in step (a). Although not limited to the theory, the presence of a trace metal element in the solvent in the step (b) increases the reactivity between the diamine and the acid dianhydride and increases the molecular weight of the polyimide, thereby improving the bending resistance to a plurality of bends. I think. The addition amount of trace metal element and trace nonmetallic element is adjusted so that the quantity of these elements with respect to polymer ((alpha)) may become the quantity demonstrated in the said << varnish >> column.

Although the conditions at the time of reaction of a process (b) are not specifically limited, For example, reaction temperature may be 0 degreeC-250 degreeC, and reaction time may be 3 to 72 hours. In order to fully advance reaction with sulfone group containing diamine, it is preferable to heat-react at 180-200 degreeC for about 12 hours. Moreover, it is preferable that it is inert atmosphere, such as argon and nitrogen, at the time of reaction.

The solvent (beta) of the varnish in this embodiment can use the solvent (reaction solvent) at the time of superposing | polymerizing a polyimide as it is. The reaction solvent is not particularly limited as long as it is a solvent in which the polyimide is dissolved. As the reaction solvent, a polar solvent is useful, and examples of the polar solvent include phenol solvents, amide solvents, lactone solvents, sulfoxide solvents, ketone solvents and ester solvents. Examples of the phenol solvents include m-cresol. Examples of the amide solvents include N-methyl-2-pyrrolidone (NMP), N, N-dimethylformamide (DMF) and N, N-dimethylacetamide (DMAc). Examples of the lactone solvents include γ-butyrolactone (GBL), δ-valerolactone, ε-caprolactone, γ-crotonlactone, γ-hexanolactone, α-methyl-γ-butyrolactone, and γ-valero Lactone, (alpha)-acetyl- (gamma) -butyrolactone, and (delta) -hexanolactone are mentioned. Examples of the sulfoxide solvent include N, N-dimethylsulfoxide (DMSO). Examples of the ketone solvents include acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone. Examples of the ester solvent include methyl acetate, ethyl acetate, butyl acetate and dimethyl carbonate. Among these, NMP and GBL are preferable from the viewpoint of solubility. From the viewpoint of further reducing the YI of the film, GBL is more preferable.

The varnish in this embodiment may contain an additive suitably. As an additive, Inorganic particles, such as a substance which shows negative birefringence, for example, strontium carbonate; And organic compounds, such as polystyrene, polyvinyl naphthalene, polymethylmethacrylate, a cellulose triacetate, and a fluorene derivative, etc. are mentioned.

As an additive, For example, Leveling agent, a dispersing agent, and surfactant for improving the coating property of a varnish; Surfactants and adhesion | attachment adjuvant for adjusting peelability and adhesiveness from a film support body; Flame retardant etc. for giving flame retardance to a film are mentioned. Other additives include, for example, antioxidants, ultraviolet light inhibitors, light stabilizers, plasticizers, waxes, fillers, pigments, dyes, foaming agents, antifoaming agents, dehydrating agents, antistatic agents, antibacterial agents, mold inhibitors, crosslinking agents, heat stabilizers, imidating agents, and the like. Can be mentioned.

As the additive, since one kind of additive may be used for a plurality of uses, such as a phosphate ester compound having a plasticizing effect and a flame retardant effect, for example, the use is not limited, but as the structure of the compound, for example, a phosphite system Compound, Phenolic Compound, Thioether Compound, Hydrazine Compound, Amide Compound, Benzotriazole Compound, Triazine Compound, Isocyanuric Acid Compound, Hindered Amine Compound, Hindered Phenolic Compound, Phosphate Ester Compound , Phosphazene compounds, urethane compounds, acrylic compounds, methacryl compounds, epoxy compounds, isocyanate compounds and the like.

The additive added to the polyimide varnish may be contained in the polyimide film as it is.

<< polyimide film >>

The polyimide film of this embodiment is obtained from the varnish of this embodiment demonstrated above. The polyimide film of this embodiment may be a polyimide film containing polyimide as a main component. The structure of a polyimide corresponds to the structure of the polyimide demonstrated by the said << varnish >> column. In this specification, a film "contains a polyimide as a main component" means containing 50 mass% or more of polyimides based on the total mass of a film. The polyimide film preferably has a polyimide of at least 60 mass%, more preferably at least 70 mass%, even more preferably at least 80 mass%, even more preferably 90 mass, based on the total mass of the film. % Or more, and particularly preferably composed of a polyimide film.

The polyimide film which concerns on this embodiment may be a polyimide film formed on the surface of a support body, for example, and may be a supportive film (independent film) even if there is no support body. It is preferable from the viewpoint of maintaining the strength as a film substrate that the polyimide film of this embodiment is a supportive film (independent film) even if there is no support body. In this specification, a supportive film means the film which has a breaking elongation of 5% or more. About the film which has a support body, when the polyimide film which peeled off a support body has a breaking elongation of 5% or more, it corresponds to the film with support.

In addition, as a measuring method of breaking elongation, the method described in (evaluation of breaking elongation and breaking strength) mentioned later can be used.

Since the polyimide film of this embodiment can be used as a substitute for glass similarly to a PET film and a COP film, and is excellent in bending resistance, for example, the polyimide of this embodiment is applied to a foldable display or a display following the curved surface. Even if the film is used, film breakage is less likely to occur, and the usability is good.

<Flexion resistance>

It is preferable that the polyimide film of this embodiment is not broken when it bends 100,000 times on condition of a bending radius of 2 mm, a bending angle of 135 degrees, and a load of 0.625 kg / m 2, and the trace of bending cannot be visually confirmed. When the polyimide film of this embodiment has this structure, it can use it suitably as a board | substrate of a flexible optical device.

Such bending resistance can be tested by any method as long as the above conditions can be realized, and can be performed as shown in FIG. 1, for example. The size of the test object film 1 can be 10-20 mm in width, 110 mm in length, and 5-20 micrometers in thickness. As shown in FIG. 1, the film 1 of a test object is pinched by the chuck 4 attached to the plunger 3 arrange | positioned at the upper part of the swivel 2, and passes through the center of the swivel 2 Let it hang. The film 1 is clamped with the two clamps 5 so that the two clamps 5 attached to the swivel 2 are in contact with the film 1 at the center of rotation of the swivel 2. The tip of the clamp is a curved surface having a radius of 2 mm, whereby the film 1 can be bent to a bending radius of 2 mm. At the end of the plunger 3, a weight can be set, and by changing the weight of the weight, a load of 1.25 kg / m 2 can be applied to the film 1. The swivel table 2 can repeatedly rotate by switching left rotation and right rotation. The turntable 2 is rotated left (or right) with the position of the lower end of the film in the starting state as the starting point (0 °). As the turntable 2 rotates, the lower end of the film is lifted upward while being held by the clamp 5, and the film 1 bends while contacting the clamp 5. When the bend angle 6 reaches 135 °, the rotation direction of the turntable 2 is reversed. When the film 1 passes through the starting point and the bending angle 6 reaches 135 ° again in the reverse direction, the direction of rotation of the turntable 2 is again switched. As mentioned above, the operation | movement from the starting point to the starting point, 135 degrees to the right (or left), 135 degrees to the starting point, the left (or right), and returning to the starting point is made into one bending.

It is a schematic diagram for demonstrating the state of the film after a bending test. Even if the above-mentioned bending is repeated 100,000 times, the polyimide film of this embodiment does not fracture | rupture as shown to the example of FIG. For example, if the haze of the bend of a film is measured after a bending test, it is preferable that it is 5.0 or less, More preferably, it is 3.0 or less, More preferably, it is 1.0 or less. FIG. 2 (b) shows an example of a conventional polyimide film broken when flexed about 29,000 times. FIG. 2 (c) shows an example of a PET film in which the bending trace can be visually confirmed after bending about 1,000 times.

<Yellow degree (YI)>

Yellowness (YI) of the polyimide film which concerns on this embodiment becomes like this. Preferably it is 5.0 or less, More preferably, it is 4.5 or less, More preferably, it is 4.0 or less. At this time, it is preferable that it is in the range of 0.1 micrometer-30 micrometers, and, as for the film thickness of a polyimide film, it is more preferable to exist in the range which is 1 micrometer-20 micrometers.

When using for the film board | substrate for flexible devices, it is preferable that the film thickness of a polyimide film exists in the range of 1 micrometer-10 micrometers from a viewpoint of the bending resistance improvement by thinning of a device, More preferably, it is 1 micrometer-5 It is in the range of µm.

The film of less than 10 micrometers can be produced by extending | stretching a polyimide film whose film thickness is 10 micrometers or more, for example. Polyimide varnish is apply | coated on a support body, and even if a support body is peeled off, it is temporarily dried until the polyimide film can have self-support. As the support, polyimide films such as PET film, Kapton (registered trademark of Toray DuPont), Upilex (registered trademark of Ubegosan), metal foil, and the like can be used. It is preferable that the amount of solvent which remain | survives in a solvent containing film at the time of an extending | stretching process is 0.1-20 mass% from a viewpoint of the independence of a film and stretchable workability.

The temporary dry film can be produced by stretching 1.5 to 5 times in the MD direction and / or the TD direction by biaxial stretching while heating at 150 ° C to 250 ° C while the support film is attached or peeled off on the support. Although extending | stretching may be simultaneous biaxial stretching or sequential biaxial stretching, It is preferable that it is simultaneous biaxial stretching from a viewpoint of reducing Rth of a film. The temporary drying film after extending | stretching is then subjected to this drying, and is dried until the residual solvent becomes less than 0.1 mass%.

In this embodiment, yellowness YI can also be adjusted to 2.0 or less. Thus, in this embodiment, a low yellowness can be suppressed, ie, a colorless transparent polyimide film can be obtained. In addition, "colorless transparent" as used in this embodiment refers to the state in which the total light transmittance of a film is 80% or more, haze is 2 or less, and yellowness (YI) is 5.0 or less. Therefore, the polyimide film of this embodiment can be used suitably for optical uses, such as a touchscreen and a display. For example, when using the polyimide resin which concerns on this embodiment as a board | substrate film of a transparent electrode film, the touch panel element is produced in at least one surface of the upper and lower surfaces of a board | substrate film, and the side which opposes the surface of a board | substrate film or the surface of a board | substrate film Even if the viewing surface is used, the coloring and brightness of the screen are not adversely affected.

〈Rthation〉

The retardation (Rth) of the polyimide film of this embodiment is a conversion value which made film thickness 15 micrometers, Preferably it is 100 nm or less, More preferably, it is 50 nm or less, More preferably, it may be 20 nm or less. Although Rth may be negative, Preferably it is a value larger than -5 nm.

For example, as described in Non-Patent Document 1, the acid dianhydride and diamine skeleton used in general high heat-resistant polyimide resins have high planarity and aromatic ring density, and when coated and dried on a glass substrate, It is generally known that the orientation of a polyimide chain with respect to anisotropy arises, anisotropy is exhibited in the refractive index of an in-plane direction and an out-of-plane direction, and the retardation (Rth) increases. In general, as a method of reducing the anisotropy of the refractive index, a method of introducing a curved structure to suppress molecular orientation during drying and a method of diluting the concentration of an aromatic ring having a large electron density are known. Moreover, as described in patent document 4, the method of obtaining the colorless transparent film with small anisotropy is also known by using the polyimide which introduce | transduced the bending group like 4,4'- diamino diphenyl sulfone as a diamine. However, in order to obtain a colorless transparent film having a small anisotropy of the refractive index, a method of forming a polyimide film via a polyamic acid film made of a solution of polyamic acid as a precursor soluble in a solvent was common. In this case, since a polyamic-acid film is inferior in strength and it is difficult to make a freestanding film, there existed a problem that handling property deteriorated.

On the other hand, the polyimide varnish of this embodiment, especially the polyimide film made from the polyimide varnish containing the polyimide represented by the said Formula (1), has low yellowness and retardation (Rth), and also has mechanical strength. It can manufacture as an excellent self-supporting film. For this reason, the polyimide film of this embodiment can be utilized for handling property suitably as optical device uses, such as a touch panel and a display, for example.

In the conversion value which made film thickness 15 micrometers, when retardation (Rth) is 100 nm or less, when using the polyimide film of this embodiment as a board | substrate film of a transparent electrode film, at least one surface of the upper and lower surfaces of a substrate film, for example Even when a touch panel element is manufactured and used as the viewing surface, since it hardly adversely affects the rainbow stain of a screen, it is preferable. Although not limited to the theory, the structure represented by the general formula (A-1) and the general formula (A-5) are structures in which the SO ₂ group is bent, and the flexure structure is fixed because it is an sp2 orbit. Therefore, it is thought that the structure represented by general formula (A-1) and the aromatic group contained in general formula (A-5) exist randomly, without lining up in one direction. That is, when the structure represented by general formula (A-1) and general formula (A-5) exist in a polyimide frame | skeleton, it is thought that the refractive index difference of in-plane direction and out-of-plane direction is small, and Rth can be reduced.

The polyimide film of the present embodiment can be used as a substitute for glass in the same manner as the PET film and the COP film, and furthermore, since the polyimide film of the present embodiment has excellent bending resistance, it has followed the folding display body and curved surface. It can be used for a display body.

<< manufacturing method of polyimide film >>

The polyimide film can be obtained, for example, by forming a varnish of the present embodiment on the surface of the support by coating or the like, and then heating the varnish.

The manufacturing method of the polyimide film in this embodiment is, for example: coating the varnish of this embodiment on a support body; Conditioning a solvent and forming the solvent containing film (henceforth an "intermediate film") containing 0.1 mass%-20 mass% of a solvent; Furthermore, it can obtain by heating an intermediate film and performing this drying until it becomes less than 0.1 mass% of a solvent. You may implement the process of extending | stretching an intermediate film suitably.

As a varnish film-forming method, well-known coating methods, such as a spin coat, a slit coat, a slot die coat, and a blade coat, are mentioned, for example.

Examples of the support include a glass substrate such as an alkali glass substrate and an alkali free glass substrate (Eagle XG (registered trademark), manufactured by Corning Corporation); Metal substrates such as metal substrates such as copper substrates, aluminum substrates and SUS substrates; Plastic films such as colored polyimide films, polycarbonate films, PET films and the like such as Upilex® film (manufactured by Ubegosan) and Kapton® film (manufactured by Toray DuPont); Metal foils such as copper foil, aluminum foil, SUS foil and the like. However, heating and drying with respect to a polyimide varnish can be performed even if there is no support body, and the kind of support body is not specifically limited. Here, the substrate as the support means high rigidity and unsuitable for bending and the like, and the film or film substrate means flexible and capable of bending.

The temperature in the conditioning tank is generally 50 ° C to 350 ° C, preferably 70 ° C to 200 ° C, and more preferably 100 ° C to 150 ° C.

The temperature in this drying is generally 100 degreeC-350 degreeC, Preferably it is 150 degreeC-320 degreeC, More preferably, it is 180 degreeC-300 degreeC.

The temperature in extending | stretching is 200 degreeC-400 degreeC generally, Preferably it is 200 degreeC-350 degreeC, More preferably, it is 250 degreeC-350 degreeC. The temperature in drying after extending | stretching is 200 degreeC-400 degreeC generally, Preferably it is 200 degreeC-350 degreeC, More preferably, it is 250 degreeC-350 degreeC.

By performing temperature of 150 degreeC-350 degreeC with inert gas atmosphere with respect to a varnish, a solvent can be removed and a polyimide film can be formed. Drying can be performed also in air | atmosphere atmosphere, and is not specifically limited.

Examples of the solvent (β) for varnish suitable for film forming include m-cresol, NMP, DMF, DMAc, GBL, DMSO, acetone, diethyl acetate, and the like. Among these, the low YI of a polyimide film can be ensured by using GBL for a solvent.

As described above, the solvent is almost removed by heating and drying the polyimide varnish. From the viewpoint of obtaining desired YI, Rth and flexural resistance and not impairing desired physical properties, the content of the solvent, such as GBL, in the polyimide film is preferably smaller than 3% by mass, more preferably smaller than 1% by mass, It is more suitable that it is 0.5 mass% or less. In addition, at least about 0.01 mass% of GBL may be contained in a polyimide film as remainder.

The manufacturing method of the polyimide film of this embodiment has the method of forming a polyimide film from the polyimide varnish of this embodiment imidated previously, and the method of forming a polyimide film from the polyimide precursor varnish of this embodiment. have.

As a method of forming a polyimide film from a polyimide varnish, the solubility of the polyimide in the solvent is good, and even if the polyimide varnish is applied to the support, temporarily dried and the support is removed, the polyimide film is supportable. This film (freestanding film) can be maintained. Therefore, the polyimide film after temporary drying containing 0.1 mass%-20 mass% of a solvent in the free state not supported by a support body (also called "temporally dried film", "intermediate film", and "solvent containing film" in this specification). Can be heated to obtain a polyimide film having a solvent content of less than 0.1% by mass in a state where the orientation of the polymer is small. Moreover, you may extend | stretch and heat a temporary dry film in the free state which is not supported by a support body.

In the method of heating and imidizing in the state which apply | coated the varnish containing a polyimide precursor on a support body, the residual distortion of a polyimide film tends to become large by the distortion by the expansion difference with a support body. Moreover, when imidating from the polyamic-acid film which is a polyimide precursor, since a polyamic-acid film is inferior in strength, a support is needed and it is difficult to obtain a freestanding film after temporary drying. Moreover, since distortion due to dehydration shrinkage occurs, the residual distortion of the polyimide film tends to be large. Therefore, when forming a polyimide film into a film from the varnish containing a polyimide precursor, it is preferable to apply and apply on support with heat resistance, such as a colored polyimide film.

Since the polyimide film in this embodiment can obtain higher breaking elongation and breaking strength, it has the outstanding bending resistance.

In another embodiment, you may make a laminated body by putting a functional layer on the surface of a polyimide film. The functional layer can be obtained by, for example, depositing a transparent electrode layer on a surface of a polyimide film with a sputtering apparatus. When a laminated body has a polyimide film on both surfaces, the transparent electrode layer may be formed in both surfaces of a laminated body. It is preferable to form at least 1 or more transparent electrode layers in the polyimide film of both surfaces of a laminated body, respectively. Moreover, between the transparent electrode layer and a polyimide film, the undercoat layer for providing smoothness, the hard coat layer for giving surface hardness, the index matching layer for improving visibility, and the gas barrier layer for giving gas barrier property It may have another layer. The hard coat layer for providing surface hardness and the index matching layer for improving visibility may be laminated | stacked on the transparent electrode layer and a polyimide film. The laminate is particularly suitable for use in touch panel materials such as transparent electrode films.

<< flexible display device >>

The flexible display device of this embodiment has the polyimide layer of this embodiment. As a flexible display device, an organic electroluminescent display, such as a bottom emission type flexible organic electroluminescent display, a top emission type flexible organic electroluminescent display, or a flexible liquid crystal display is mentioned.

The varnish and polyimide film of this embodiment are suitable for forming the polyimide layer used for a flexible display device. Preferably, the flexible display device can be manufactured using the varnish or polyimide film of this embodiment.

The flexible display device of this embodiment may have a polyimide film as a film base material of at least 1 layer used for the display part. The polyimide film of this embodiment may be a polyimide film formed on the surface of a support body, or a film (supporting film) with supportability even if there is no support body. It is preferable that a polyimide film is a self-supporting film from a viewpoint of applying to a processing process as a roll film. The polyimide film of this embodiment can be used as a substitute for glass similarly to PET film or COP film, and can also be used for the display body which followed the folding display body or curved surface.

When using for the film substrate for flexible display devices, it is preferable that the film thickness of a polyimide film exists in the range of 1 micrometer-50 micrometers from a viewpoint of thinning of a device and the improvement of bending resistance, More preferably, it is 1 micrometer-25 micrometers In range

When using the polyimide film of this embodiment for a flexible display device, the said flexible display device is equipped with a light source, Comprising: The light of this light source passes through the polyimide film of this embodiment, and is output so that it may be output to the exterior of a flexible display device. It is preferable.

<< lamination >>

In this embodiment, a laminated body can be manufactured by forming a transparent electrode layer on the surface of a polyimide film.

A laminated body can be obtained by forming a transparent electrode layer into a film by the sputtering apparatus on the surface of a polyimide film. The polyimide film may have a support or may be a single layer not having a support. The laminate may have transparent electrode layers on both sides of the polyimide film. At this time, it is preferable to have at least 1 or more transparent electrode layers on both surfaces of a polyimide film, respectively. Moreover, between the transparent electrode layer and a polyimide film, the undercoat layer for providing smoothness, the hard coat layer for giving surface hardness, the index matching layer for improving visibility, and the gas barrier layer for giving gas barrier property It may have another layer. The hard coat layer for providing surface hardness and the index matching layer for improving visibility may be laminated | stacked on the transparent electrode layer and a polyimide film. The laminate of the present embodiment is suitable for use in a touch panel material such as a transparent electrode film.

When forming a transparent electrode film, although the film-forming process of the transparent electrode layer to the polyimide film surface is performed in the low temperature range of 80-100 degreeC, for example, in order to express desired performance actually, sputtering at high temperature is performed, It is preferable to form the transparent electrode layer with low specific resistance. A transparent electrode layer can be made into the structure formed in both surfaces of a polyimide film. Thus, for example, touch panel elements can be arranged on both surfaces.

At this time, when the temperature for forming the transparent electrode layer is high in the glass transition temperature (Tg) of the polyimide film forming the film formation surface, problems such as shrinkage or breakage of the polyimide film occur in a high temperature region. Generally, when forming a transparent electrode layer on a PET film, sputtering in about 80 degreeC lower than about 100 degreeC which is glass transition temperature (Tg) of PET film is performed. On the other hand, the polyimide film which concerns on this embodiment has a high glass transition temperature (Tg) of about 250 degreeC or more (based on 15 micrometers in thickness of a film), and is excellent in heat resistance. That is, high bending resistance can be maintained even when exposed to high temperature of 200 ℃ or more. Therefore, sputtering about 150-250 degreeC is performed to the surface of the polyimide film 10 of this embodiment, for example, and the transparent electrode layer with low specific resistance can be formed into a film.

In the present embodiment, the polyimide preferably has a breaking strength of 100 MPa or more based on a thickness of 15 μm of the polyimide film from the viewpoint of improving the yield when forming the transparent electrode layer 21.

In addition, as for the polyimide film which concerns on this embodiment from the viewpoint of improving the performance of a transparent electrode film, it is preferable that glass transition temperature (Tg) is 250 degreeC or more based on the thickness of 15 micrometers as mentioned above. Do.

Example

Hereinafter, although this invention is demonstrated in more detail, for example, these are described for description, and the scope of the present invention is not limited to the following example. Various evaluations in the example were performed as follows.

Measurement and Evaluation Method

<Evaluation (flexion test) of bending tolerance>

Evaluation of the bending resistance of a polyimide film used MIT type repetition bending tester (MIT-DA, Toyo Seiki Seisakusho Co., Ltd.) after adjusting a film at 25 degreeC and 50% of a relative humidity for 24 hours. In a state where a weight of 0.625 kg / mm 2 was applied to a test piece having a width of 15 mm, a length of 100 mm, and a thickness of 7 to 20 µm, a bending radius R of 2 mm, a bending angle of 135 °, and a speed of 90 times / min The repeated bending test in 100,000 round trips was done on condition of the following. After the test, the samples were peeled from the apparatus to obtain flexural resistance evaluation results.

The obtained bending resistance was divided according to the following criteria.

(Bend resistance rank)

○ (good): The thing which can not visually confirm a trace of bending

× (poor): the trace of bending can be visually confirmed or the haze is 5.0 or more

In addition, haze was measured using the D65 light source with the Konica Minolta Corporation spectrophotometer (CM3600A).

<Measurement of transmittance>

The transmittance | permeability of the polyimide varnish was measured on the following conditions by the ultraviolet-visible absorption spectrum measurement, after adjusting the solid content concentration of polyimide varnish to 20 mass%. The apparatus used UV / VIS SPECTROPHOTOMETER (V-550, JASCO). The background was measured by placing cells filled with the same solvent as the varnish in the reference chamber and the sample chamber. The transmittance spectrum was measured by arranging a cell filled with the same solvent as the varnish in the reference chamber and arranging a cell filled with the measurement sample in the sample chamber. From the obtained spectral data, the value in optical path length 10 mm and wavelength 450 nm was made into the transmittance | permeability.

Device: UV / VIS SPECTROPHOTOMETER (V-550, manufactured by JASCO)

Cell size: 10mm in thickness X 10mm in width X 400mm in height

Measuring wavelength: 300 nm-800 nm

Band Width: 2.0 nm

Scanning speed: 200 nm / min

The transmittance | permeability obtained was divided according to the following criteria.

(Transmission rank)

(Excellent): The transmittance | permeability is more than 60%.

(Good): The transmittance | permeability is 45% or more and 60% or less.

X (poor): The transmittance | permeability is less than 45%.

<Measurement of Metal Elements, Phosphorus, and Silicon>

The content of the metal elements, phosphorus and silicon in the varnish was measured by ICP-AES measurement. It weighed 0.5 g of a raw material, and nitric acid + hydrochloric acid, nitric acid → → the adjustment (定容) the sample was wet decomposed with nitric acid to perchloric acid + 25 mL, ICP-AES was carried out for qualitative analysis.

<Measurement of weight average molecular weight (Mw) and number average molecular weight (Mn)>

The weight average molecular weight (Mw) and the number average molecular weight (Mn) were measured by gel permeation chromatography (GPC) under the following conditions. As a solvent, 24.8 mol / L lithium bromide monohydrate (made by Wako Pure Chemical Industries, Purity 99.5%) using N, N-dimethylformamide (made by Wako Pure Chemical Industries, Ltd., for high-speed liquid chromatography), and before measurement The addition of 63.2 mol / L phosphoric acid (made by Wako Pure Chemical Industries, Ltd., for high performance liquid chromatography) was used. In addition, the analytical curve for calculating a weight average molecular weight was produced using standard polystyrene (made by Tosoh Corporation).

Column: TSK-GEL SUPER HM-H × 2

Flow rate: 0.5 mL / min

Column temperature: 40 ℃

Pump: PU-2080 (manufactured by JASCO Corporation)

Detector: RI-2031Plus (RI: Differential Refractometer, manufactured by JASCO)

   UV-2075 Plus (UV-Vis: ultraviolet visible absorber, manufactured by JASCO Corporation)

<Evaluation of Surface Smoothness (Ra)>

The measurement area (50 micrometers x 50 micrometers) of the film layer side of the laminated body was scanned using the nanoscale hybrid microscope (VN8000, Gence Corporation), and the arithmetic mean roughness Ra of the surface was measured. .

<Evaluation of Yellowness (YI)>

The yellowness (YI value) of the polyimide film was measured using the D65 light source with the Konica Minolta Corporation spectrophotometer (CM3600A). In addition, unless otherwise indicated, the measurement was performed about the film of 20 +/- 1micrometer film thickness as a sample.

The obtained yellowness (YI) was divided according to the following criteria.

(YI rank)

(Excellent): YI of a film is two or less.

(Good): YI is more than 2 and is 4 or less.

X (poor): YI is more than four.

Next, the synthesis conditions of a polyimide and the manufacturing conditions of a polyimide film are demonstrated concretely.

`` Abbreviated name of acid dianhydride and diamine. ''

Mountain Anhydride

6FDA: 4,4 '-(hexafluoroisopropylidene) diphthalic acid dianhydride

ODPA: 4,4'-oxydiphthalic acid dianhydride

PMDA: 4, pyromellitic dianhydride

BPDA: 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride

HPMDA: Hydroxypyromellitic Acid 2 Anhydride

TDA: 1,3,3a, 4,5,9b-hexahydro-5- (tetrahydro-2,5-dioxo-3-furanyl) naphtho [1,2-c] furan-1,3- Dion

BODA: Bicyclo [2,2,2] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (also referred to as BCDA)

Diamine

TFMB: 2,2'-bis (trifluoromethyl) benzidine

3,3'-DDS: 3,3'-diaminodiphenylsulfone

4,4'-DDS: 4,4'-diaminodiphenylsulfone

CHDA: cyclohexyldiamine

14BAC: 1,4-bis (aminomethyl) cyclohexane

BANBDA: Bis (aminomethyl) norbornane

BAPB: 4,4'-bis (4-aminophenoxybiphenyl)

BAPDB: α, α'-bis (4-aminophenyl) -1,4-diisopropylbenzene

<< synthesis example of polyimide varnish >>

The polyimide varnish and the polyimide precursor (polyamic acid) varnish were produced as shown to the following synthesis examples and the comparative synthesis examples. Table 1 shows the amount (mol%) of acid dianhydride and diamine of the starting materials. Trace metal was added to the reaction solution with the raw material, and each Example and the comparative example were created. Table 2 shows the types and amounts of added metals.

Synthesis Example 1-1

22.19 g (69.30 mmol) of 2,2'-bis (trifluoromethyl) benzidine (TFMB) while introducing nitrogen gas into a 500 mL separable flask with a stir bar with a Deanstock tube and a reflux tube at the top, γ 50.00 g of butyrolactone (GBL) were added. Subsequently, 31.09 g (70.00 mmol) of 4,4 '-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) and 22.28 g of GBL were added at room temperature. The solution was stirred at room temperature for 6 hours to produce a polyimide precursor, and after adding 26.02 g of toluene at room temperature, the temperature was raised to 160 ° C and heated to reflux at 160 ° C for 1 hour to perform imidization. After imidation was completed, the temperature was raised to 180 ° C and the reaction was continued while taking out toluene. After the reaction for 12 hours, the oil bath was removed and returned to room temperature, and GBL was added so that the solid content was 20% by mass, thereby obtaining a polyimide GBL solution (hereinafter also referred to as polyimide varnish).

Synthesis Example 1-2

A polyimide varnish was synthesized in the same manner as in Synthesis Example 1-1, except that the addition of metal was changed as shown in Table 2.

Synthesis Example 1-3

A polyimide precursor varnish was synthesized in the same manner as in Synthesis Example 1-1, except that the addition of metal was changed as shown in Table 2, the reaction temperature was 80 ° C, and no imidization was performed by the heating reflux process.

Synthesis Example 2-1

A polyimide varnish was synthesized in the same manner as in Synthesis Example 1-1 except that the acid 2 anhydride and the diamine were injected and the metals were added as shown in Tables 1 and 2.

Synthesis Example 2-2

A polyimide varnish was synthesized in the same manner as in Synthesis Example 1-1 except that the acid 2 anhydride and the diamine were injected and the metals were added as shown in Tables 1 and 2.

Synthesis Example 3-1

As in Table 1 and Table 2, polyimide varnishes were prepared in the same manner as in Synthesis Example 1-1, except that the acid 2 anhydride and the diamine were injected and the metals were changed and N-methylpyrrolidone (NMP) was used as the solvent. Was synthesized.

Synthesis Example 3-2

As in Table 1 and Table 2, polyimide varnishes were prepared in the same manner as in Synthesis Example 1-1, except that the acid 2 anhydride and the diamine were injected and the metals were changed and N-methylpyrrolidone (NMP) was used as the solvent. Was synthesized.

Synthesis Example 4-1

As shown in Table 1 and Table 2, polyimide varnish was synthesized according to the procedure described below by changing acid 2 anhydride and diamine and adding metal.

12.05 g (48.51 mmol) of 4,4'-DDS and 5.16 g of 3,3'-DDS while introducing nitrogen gas into a 500 mL separable flask with a stir bar equipped with a Deanstock tube and a reflux tube. (20.79 mmol), GBL was added to 50.00 g. Then, 21.71 g (70.00 mmol) of 4,4'-oxydiphthalic anhydride (ODPA), 22.28 g of GBL, and 26.02 g of toluene were added at room temperature, and then heated up to an internal temperature of 160 ° C, and heated to reflux at 160 ° C for 1 hour. And imidization was performed. After imidation was completed, the temperature was raised to 180 ° C and the reaction was continued while taking out toluene. After the reaction for 12 hours, the oil bath was removed and returned to room temperature, and GBL was added so that the solid content was 20% by mass, thereby obtaining a polyimide GBL solution (hereinafter also referred to as polyimide varnish).

Synthesis Example 4-2

A polyimide varnish was synthesized in the same manner as in Synthesis Example 4-1, except that the acid 2 anhydride and the diamine were injected and the metals were added as shown in Tables 1 and 2.

Synthesis Example 5-1

Polyimide varnish was synthesized in the same manner as in Synthesis Example 4-1 except that the acid 2 anhydride and the diamine were injected and the metals were added as in Table 1 and Table 2, and the reaction time was changed to 7 hours.

Synthesis Example 5-2

Polyimide varnish was synthesized in the same manner as in Synthesis Example 4-1 except that the acid 2 anhydride and the diamine were injected and the metals were added as in Table 1 and Table 2, and the reaction time was changed to 7 hours.

Synthesis Example 6

Polyimide varnish was synthesized in the same manner as in Synthesis Example 4-1 except that the acid 2 anhydride and the diamine were injected and the metals were added as in Table 1 and Table 2, and the reaction time was changed to 7 hours.

Synthesis Example 7

Polyimide varnish was synthesized in the same manner as in Synthesis Example 4-1 except that the acid 2 anhydride and the diamine were injected and the metals were added as in Table 1 and Table 2, and the reaction time was changed to 7 hours.

Synthesis Example 8

As in Table 1 and Table 2, polyimide varnishes were prepared in the same manner as in Synthesis Example 4-1, except that the acid 2 anhydride and the diamine were injected and the metals were changed and the reaction time was 7 hours using NMP as the solvent. Was synthesized.

Synthesis Example 9

As in Table 1 and Table 2, polyimide varnishes were prepared in the same manner as in Synthesis Example 4-1, except that the acid 2 anhydride and the diamine were injected and the metals were changed and the reaction time was 7 hours using NMP as the solvent. Was synthesized.

Synthesis Example 10

Polyimide varnish was synthesized in the same manner as in Synthesis Example 4-1 except that the acid 2 anhydride and the diamine were injected and the metals were added as in Table 1 and Table 2, and the reaction time was changed to 7 hours.

Synthesis Example 11

Polyimide varnish was synthesized in the same manner as in Synthesis Example 4-1 except that the acid 2 anhydride and the diamine were injected and the metals were added as in Table 1 and Table 2, and the reaction time was changed to 7 hours.

Synthesis Example 12

Polyimide varnish was synthesized in the same manner as in Synthesis Example 4-1 except that the acid 2 anhydride and the diamine were injected and the metals were added as in Table 1 and Table 2, and the reaction time was changed to 7 hours.

Synthesis Example 13

The polyimide varnish was synthesized in the same manner as in Synthesis Example 4-1, except that the acid 2 anhydride and the diamine were injected and the metals were added as in Table 1 and Table 2, and the reaction time was changed to 3 hours.

Synthesis Example 14

The polyimide varnish was synthesized in the same manner as in Synthesis Example 4-1, except that the acid 2 anhydride and the diamine were injected and the metals were added as in Table 1 and Table 2, and the reaction time was changed to 4 hours.

Synthesis Example 15

Polyimide varnish was synthesized in the same manner as in Synthesis Example 4-1, except that the acid 2 anhydride and the diamine were injected and the metals were added as in Table 1 and Table 2, and the reaction time was changed to 6 hours.

Synthesis Example 16

To 5.11 g (13.86 mmol) of 4,4'-bis (4-aminophenoxybiphenyl) (BAPB) while introducing nitrogen gas into a 500 mL separable flask with a stir bar with a Deanstock tube and a reflux tube at the top. , 3,3-DDS was added to 10.32 g (41.58 mmol), 4,4-DDS to 3.44 g (13.86 mmol) and GBL to 50.00 g. Then, 21.71 g (70.00 mmol) of 4,4'-oxydiphthalic anhydride (ODPA), 22.28 g of GBL, and 25.63 g of toluene were added at room temperature, and then heated up to an internal temperature of 160 ° C and heated to reflux at 160 ° C for 1 hour. And imidization was performed. After imidation was completed, the temperature was raised to 180 ° C and the reaction was continued while taking out toluene. After 6 hours of reaction, the oil bath was removed and returned to room temperature, and NMP was added so that the solid content was 20% by mass, thereby obtaining a polyimide NMP solution (hereinafter also referred to as polyimide varnish).

Synthesis Example 17

Polyimide varnish was synthesized in the same manner as in Synthesis Example 4-1, except that the acid 2 anhydride and the diamine were injected and the metals were added as in Table 1 and Table 2, and the reaction time was changed to 6 hours.

Synthesis Example 18

A polyimide varnish was synthesized in the same manner as in Synthesis Example 4-1, except that the acid 2 anhydride and the diamine were injected and the metals were added as shown in Tables 1 and 2.

Synthesis Example 19

A polyimide varnish was synthesized in the same manner as in Synthesis Example 4-1, except that the acid 2 anhydride and the diamine were injected and the metals were added as shown in Tables 1 and 2.

Synthesis Example 20

A polyimide varnish was synthesized in the same manner as in Synthesis Example 4-1, except that the acid 2 anhydride and the diamine were injected and the metals were added as shown in Tables 1 and 2.

Comparative Synthesis Example 1

Raw material used all refined thing. When the metal ion concentration of the raw material was measured, all of Cu, Cr, Zr, Zn, Mn, Co, Pd, Ni, Rh, Al, and Fe were 0.01 ppm or less, and silicon and India were 0.01 ppm or less as well.

A polyimide varnish was synthesized in the same manner as in Synthesis Example 1-1, except that acid 2 anhydride and diamine were injected and metal addition was changed as in Table 1 and Table 2 using the purified raw materials.

Comparative Synthesis Example 2

Synthesis Example 1-1 was used except that the acid 2 anhydride and the diamine were injected and the metals were added, and N-methylpyrrolidone (NMP) was used as the solvent. Polyimide varnish was synthesized in the same manner.

Comparative Synthesis Example 3

A polyimide varnish was synthesized in the same manner as in Synthesis Example 4-1, except that acid 2 anhydride and diamine were injected and metal addition was changed as in Table 1 and Table 2 using the purified raw materials.

Comparative Synthesis Example 4

A polyimide varnish was prepared in the same manner as in Synthesis Example 4-1, except that the acid 2 anhydride and the diamine were injected and the metals were added, and the reaction time was changed to 7 hours using the purified raw materials. Was synthesized.

Comparative Synthesis Example 5

A polyimide varnish was synthesized in the same manner as in Synthesis Example 4-1, except that acid 2 anhydride and diamine were injected and metal addition was changed as in Table 1 and Table 2 using the purified raw materials.

Comparative Synthesis Example 6

A polyimide varnish was synthesized in the same manner as in Synthesis Example 4-1, except that acid 2 anhydride and diamine were injected and metal addition was changed as in Table 1 and Table 2 using the purified raw materials.

Comparative Synthesis Example 7

A polyimide varnish was synthesized in the same manner as in Synthesis Example 4-1, except that acid 2 anhydride and diamine were injected and metal addition was changed as in Table 1 and Table 2 using the purified raw materials.

The composition and evaluation result of the polyimide varnish obtained by the synthesis examples 1-1-20 and the comparative synthesis examples 1-7 are shown in the following table | surfaces.

<< production of polyimide film >>

[Examples 1 to 26]

As shown in Table 2 and Table 3, the polyimide varnish or the polyimide precursor varnish of each synthesis example was coated with a coating thickness of 150 μm on upilex (Ubegosan Co., Ltd. product number upilex 125s) as a supporting base material, and was applied at 50 ° C. to 30 ° C. Min dried. After drying the laminated body of this solvent containing film and an upilex film at 270 degreeC for 1 hour, the test result of the self-supporting film of the polyimide of the state which peeled the upilex film which is a support body is shown in Table 3 below.

[Comparative Examples 1-7]

As shown in Table 2 and Table 3, the polyimide varnish of each comparative synthesis example was coated with a coating thickness of 150 µm on upilex (manufactured by Ubegosan, product number upilex 125s) as a supporting substrate, and dried at 50 ° C for 30 minutes. After drying the laminated body of this solvent containing film and an upilex film at 270 degreeC for 1 hour, the test result of the self-supporting film of the polyimide of the state which peeled the upilex film which is a support body is shown in Table 3 below.

[Evaluation results]

As shown in Table 3, the polyimide film of this embodiment is excellent in bending resistance, surface smoothness, and transparency (YI value).

The varnish of this invention can be used for manufacture of the polyimide film used as a surface film, color filters, substrate films, such as TFT, and an insulating protective film. The polyimide film and the laminate in the present embodiment include an optical device such as a display with a touch panel function, an organic EL light emitting device, a smartphone, and a tablet terminal; Flexible optical devices such as flexible display devices, flexible solar cells, flexible touch panels, collapsible smart phones or tablet terminals; Other flexible devices such as flexible batteries; And it can use suitably for products, such as an organic electroluminescent device which has a curved surface, and an organic electroluminescent display.

1: film
2: plunger
3: chuck
4: swivel
5: clamp
6: bend angle

Claims (30)

A varnish containing a polymer (α) and a solvent (β),
The polymer (α) is a polyimide or polyimide precursor,
The varnish includes at least one metal element belonging to a typical metal element having an atomic weight of 26 or more and 201 or less, or a transition metal element having an atomic weight of 26 or more and 201 or less, except for an alkali metal and an alkaline earth metal.
The varnish in which at least 1 sort (s) of the said metal element contained in the said varnish exists 0.05-500 ppm with respect to the said polymer ((alpha)). The varnish according to claim 1, wherein the varnish has a transmittance of light having a wavelength of 450 nm measured at an optical path length of 10 mm when the concentration of the polymer (α) in the solvent (β) is 20% by mass or more. The varnish according to claim 1 or 2, wherein the metal element includes at least one selected from the group consisting of Zn, Zr, Cu, Cr, Mn, Co, Pd, Ni, Rh, Al, and Fe. . The varnish according to any one of claims 1 to 3, wherein at least one of the metal elements included in the varnish is present in an amount of 0.05 to 100 ppm with respect to the polymer (α). The varnish of claim 3 wherein the metal element comprises Zn. The varnish of claim 3 wherein the metal element comprises Zr. The varnish of claim 3 wherein the metal element comprises Cu. The varnish according to claim 3, wherein the metal element comprises Cr. The varnish of Claim 3 in which the said metal element contains at least 1 sort (s) chosen from the group which consists of Mn, Co, Pd, Ni, Rh, and Al. The varnish according to claim 3, wherein the metal element comprises Fe. The method of claim 3, wherein the metal element comprises Fe,
Fe is a 50 to 500 ppm present for the polymer (α) varnish. The varnish according to any one of claims 1 to 9, wherein the varnish further includes a typical nonmetallic element selected from the group consisting of P and Si,
The varnish in which at least 1 sort (s) of the said typical nonmetallic element contained in the said varnish exists in 0.05-100 ppm with respect to the said polymer ((alpha)). The varnish according to any one of claims 1 to 12, wherein the polymer (α) is a polyimide. The varnish according to claim 13, wherein the solvent β is γ-butyrolactone. 15. The varnish of claim 14 wherein the metal element comprises Cu. The varnish according to claim 1, wherein the total amount of the metal elements contained in the varnish is 0.05 to 500 ppm with respect to the polymer (α). The varnish according to any one of claims 1 to 14, wherein the varnish is used for forming a polyimide layer of a flexible display device or a polyimide layer of an organic EL light emitting device. The polyimide film obtained from the varnish as described in any one of Claims 1-17. The organic electroluminescent device which has the polyimide film of Claim 18. The flexible display device which has the polyimide film of Claim 18. The display device of claim 20, wherein the flexible display device further comprises a light source.
And the polyimide film is disposed at a position such that light from the light source passes through the polyimide film and is output to the outside of the flexible device. A flexible display device having a polyimide layer containing a polymer (α),
The polyimide layer contains at least one metal element belonging to a typical metal element having an atomic weight of 26 or more and 201 or less, or a transition metal element having an atomic weight of 26 or more and 201 or less, except for an alkali metal and an alkaline earth metal.
At least 1 sort (s) of the said metal element contained in the said polyimide layer exists 0.05-500 ppm with respect to the said polymer ((alpha)). The flexible display device according to claim 22, wherein at least one of the metal elements contained in the polyimide layer is present in an amount of 0.05 to 100 ppm with respect to the polymer (α). The flexible display device of claim 22, wherein the metal element includes at least one selected from the group consisting of Zn, Zr, Cu, Cr, Mn, Co, Pd, Ni, Rh, Al, and Fe. The flexible display device of claim 24, wherein the metal element comprises at least one selected from the group consisting of Zn, Zr, Cu, and Cr. The method of claim 24, wherein the metal element comprises Fe,
Fe is 50 to 500 ppm present with respect to the said polymer ((alpha)). The flexible display device according to claim 22, wherein the total amount of the metal elements contained in the polyimide layer is 0.05 to 500 ppm with respect to the polymer (α). The display device of claim 27, wherein the flexible display device further comprises a light source.
The polyimide layer is disposed at a position such that light from the light source passes through the polyimide layer and is output to the outside of the flexible display device. As a method for producing a polyimide varnish, the method is
(a) dissolving diamine and an acid dianhydride in a solvent to produce a polyimide precursor,
(b) heating the polyimide precursor in the solvent to produce a polyimide,
In the step (b), at least one metal element selected from the group consisting of Zn, Zr, Cu, Cr, Mn, Co, Pd, Ni, Rh, Al and Fe is present in the solvent. Method of making varnishes. The method for producing a polyimide varnish according to claim 29, wherein the metal element comprises Cu.

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